A leading academic says New Zealand has become a "de facto ally" of the United States after signing a sweeping agreement on military cooperation in Washington early today.

The Washington Declaration was signed by US Defence Secretary Leon Panetta and Defence Minister Jonathan Coleman at the Pentagon today.

Coleman said the declaration foreshadowed greater cooperation in key areas including maritime security, counter terrorism, humanitarian assistance and disaster relief in the region and promoted peace keeping and peace support initiatives.

But he rejected suggestions the declaration was "Anzus in drag" and said it affirmed New Zealand's independent foreign policy stance.

Victoria University Professor Robert Ayson said the announcement confirmed New Zealand was now "a de facto ally of the United States".

"The declaration endorses the Obama Administration's pivot to Asia through the commitment of both countries to build their maritime security presence and capabilities.

"The declaration does not spell out the specifics of the enhanced security cooperation which will occur between the US and New Zealand but we can already see evidence of this in the expanding array of military exercises involving both the US and New Zealand including the forthcoming RIMPAC exercise off Hawaii," Ayson said.

"At a time when China's growing influence is the major regional trend, some observers will see the Declaration as evidence of New Zealand's growing alignment with Washington rather than a sign of what the Key government refers to as New Zealand's independent foreign policy."

The declaration comes nearly three decades after the Anzus bust-up which saw New Zealand suspended from the three party military pact between New Zealand, the US and Australia over its nuclear-free legislation.

A retaliatory freeze slapped on military cooperation, including training and exercises, by the US has only recently been lifted.

Labour today welcomed the declaration and stressed the importance of New Zealand maintaining an independent foreign policy.

"As a small country, New Zealand wins respect from speaking from the perspective of its own values, principles and interests, not anyone else's," the party's foreign affairs spokesman Phil Goff said.

"The days are long gone where New Zealand simply follows the position of any other nation whether it is the UK, Australia or the US."

Goff said New Zealand's case for a seat on the United Nations Security Council in 2012 was reliant on our government being "seen to act with integrity and independence as a good international citizen".

"The reality of that means that New Zealand ought not to enter or re-enter formal defence alliances, including Anzus, which would prevent New Zealand from taking positions on any international issues on their merits.

"This arrangement appears simply to reaffirm cooperation between New Zealand and a friendly country on issues where it is sensible to talk and work together on matters of mutual concern."